Identity Testing
Analytical tests confirming that a pharmaceutical product contains the correct active ingredient. For peptide drugs, identity testing typically uses mass spectrometry (confirming molecular weight), amino acid analysis (confirming composition), and comparison to a reference standard.
Technical Context
Identity testing must be specific enough to distinguish the target peptide from closely related sequences. Methods: mass spectrometry (confirming molecular weight matches theoretical — primary identity method), amino acid analysis (hydrolysing the peptide and quantifying constituent amino acids — confirms overall composition but not sequence order), peptide mapping (enzymatic digest + LC-MS — confirms sequence coverage), HPLC retention time (comparing to authenticated reference standard — confirms chromatographic identity), and infrared spectroscopy (fingerprint comparison to reference spectrum). For quality control, at least two orthogonal identity methods are typically required. For peptide drugs with post-translational modifications (glycosylation, PEGylation), identity testing must also confirm the modification. Biosimilar identity testing requires extensive analytical comparison demonstrating high similarity to the reference product across multiple structural attributes.